Block-signal system.



L. A. HAWKINS. BLOUK SIGNAL SYSTEM. APPLICATION I-ILBD 811F121, 190s. nnxnwnn 0011.17, 190a.

a snnn'rs-snnnr 1.

m WE/V 70/? z. nCXTH'k/HS Patented July 27, 1909.

L. A. HAWKINS. BLOUK SIGNAL SYSTEM. APPLIOA'I'IOH FILED 211M221. 100a. nnnnwnn 001'. 1?. 1903.

Patented July 27, 1909.

sauna-sum a.

A A 4 A K f x X W/T/VES 51:5:

' doctor for the power-current.

UNITED STATES PATENT OFFICE.

LAURENCE A. HAWKINS, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

BLOCK-SIGNAL SYSTEM.

To all whom it may concern:

Be it known that KINS, a citizen of the United States, residing at Schenectad county of Schenectady, State of New new and useful Improvements in Block-Sig nal Systems, of which the following is a specification.

My invention relates to block-signal systems for electric railways employing the rails as return conductor for the ower current. When the rails must be use both for the power-current and for the signal-current two arrangements of rail connections have been proposed heretofore. Inone of these systerns one real is continuous to transmit power-current, and the other rail is sectioned to divide the track into blocks. In the other arrangement one or both rails are sectioned, and inductive bonds are employed between adjacent blocks to permit the flow of powercurrent, while preventing the flow of signal current. The first of these arrangements utilizes only half of the rails as return conductor, while the second arrangement involves the use of large and exceedingly costly bonds.

By my invention, in the case of a road having a plurality of arallel tracks, 'nearl all of the rails are 'emp oyed as return con uctor, without resortin to inductive bonds or special devices 0 any kind.

My invention consists in sectionaling one rail of each traclr and connecting rail sections of different tracks to. form a continuous con- For instance, in a double-track road alternate sections of each track may be connected with the adjacent sections of the other track, so as to form a continuous conductor. Thus, threefourths of the rails are utilized as return conductor. If more than two tracks are emloyed, a still greater proportion of-rails may e employed.

Mynnvention will best be understood by reference to the accompanying drawings, in which Figure 1 shows a double-track electric railwa with the track circuits arranged in accorc ance with my invention; Fig. 2 shows a siinilar arrangement of rail connections with the signal-circuits modified; and Fig. 3 shows the rail connections for four parallel tracks.

Referring first to Fig. 1, A and A repre- Specification of Letters Patent. Application filed September 21, 1906, Serial No. 385,579. Renewed October 17, 1908.

I, LAURENCE A. HAW-.

ork, have invented certam' erators, the

each track has its sectional rail connecte Patented July 27, 1909.,

Serial Np. 158,300.

sent the rails of two parallel tracks, each of which has one rail continuous and the other sectioned. B and B represent the suplply1 conductors for the power-current, w 10 are connected to one terminal of the powergenerator 0. This generator, which may supply either direct or low-frequency alternatmg-current, has'its other terminal con v nected directly to one rail of one track and to both rails of the other track through the differential choke-coil c. D and D represent high-freiuency alternating-current gen requenc of the currents delivered by'the two eing different. (1, d and d represent line-wiressupplied from these generators; the wire (1 being a com mon'return for the currents of both frequen.-'

'cies. The signal-currents are supplied to the blocks by transformers, thep'rimaries' of which are connected to theline-wires 6,11 and d, while the secondaries are connected to the track. Thustransformer E supplying the left-hand block in the track A,

ias its primary connected to line-wires d and ri and its secondary connected across the track-rails through a small resistance e,- which may be employed to reduce the flow of power-current throu h the transformer se'gondaryJ A relay F is connected to the ot er end of the block, and is of a type which responds -onl to current of the frequency supplied to t 1e block by the transformer E. For this purpose a relay having two co-acting windings, one connected to the track and the other so pl ed independently of the track circuit wit current of the same frequency, is employed. I have shown a relay in which the two windin s are relatively movable, but it will be on erstood that any other suitable'formof relay, such as the well known induction type, may be employad instead. The relay F controls the signa for that block. It will be seen that every at both ends to the adjacent sectional rails of the other track, so as to form a continuous conductor, making with the two continuous rails, three return conductors for the powereurrent, thereby utilizing three-fourths of the rail material. The block to which. transformer E and relay F are connected is conse uently in electrical connection with the bloc to which transformer E and relay F are connected. In order to prevent other block of h -cies, and the relay 15'" and transformers current from the transformer E affecting the relay F", transformers E and E are connected to line-wires of different frequenis connected to the same line-wires as transforhger E. Consequently, this relay, while re ponsive to the current supplied by transformer E is not affected by the current supplied by transformer E. The nearest transformer of the same frequency as relay F, which is in electrical connection with it, is three blocks away. This distance is too great for any efiective current-flow, and even this transformer can be arranged so that it cannot operate relay F b reversing its connections to the track. his reverse connection is shown in transformers E" and E" of track A. Ilhus, the relay is as effectively protected from any currents which can cause it to produce a false indication as if its block were electrically insulated from all others.

The operation of the system is as follows: With a train in a block, as indicated at H roceeding in the direction of the arrow, reay F is short-circuited and signal G is at dan er. As soon as the trainpassesout of t at block into the next one, the short circuit is removed and the relay F will clear its signal, while the relay F will put its signal at danger. A train at the. point indicated by H will not affect the rela F if a high frequency current is em loye ,for the signal circuits, since the ra: s offer a high impedance to the flow ofalternatingcurrent and the train is a block or more awa from the rela F until it passes u on the lock supplied y transformer E, w an it is no longer in position to shunt the rela F". Thus, the signal apparatus for eac block operates precisely as though the block were entirely isolated from all others, still at the same time'a third conductor is secured for the power current. In order to prey, ,false indlcations, due to failures of in ng foints, the relays ocks having their V a p ated, may be connected asfihown. For instance, a fallure of the insul ,i oint between relay F. and transformer will do no', harm, since the transformer is connectedtd assume, of different frequency the insu a transformer is taken care of by the fact that transformers E and E are reversely "seetional rails *insu connected so that the only effect of current throu h relay F from transformer F would be to old the signal in open-circuit position.

Now, referrin to Fig. 2, an arrangement is shown in which eakage-current is decreased,

7 so that only one frequency need be employed if there is an objection to the employment of two. In this figure the transformers E and E. which sup y the blocks, the sectional rails of whic are electrically connected,

. gr from the relay, wlrilefa b'reak in"s tllfijOiIIil between relay F and it" 'e second'ti'iaclrfwliuld be have their secondaries connected to the centers of the blocks, and two relays arepro vided, one at each end of the b ock, with their contacts in series, so-that either relay can put the signal at danger. With this arrangement each relay is separated from its own transformer by half a block length, while it is separated from the next transformer, to whlch it is electrically connected, by a distance equal to a block and a half. Consequently, leakage-currents,-that is, currents which flow from one transformer through relays other than that of the same block, are reduced; and furthermore, owing to the proportional distance between each relay and its own transformer, and between the same rela and the 'next nearest transformer, a sing e frequency may be employed for all the signal-circuits with perfect safety. Furthermore, the transformers E and E may be oppositely connected so that the nearest transformer which could send a current through relay F, which would tend to hold it in clear osition, would be distant three and one-hal blocks. With even a lowfrequency alternating-current this dists is, of course, entirely too greatfor internal-- ence, with one relay by current from the transformer of another block. Furthermore, there is less likelihood with this arrangement of a train in one block short-circuiting a relay two blocks ahead. For instance, with a train in the block supplied by transformer E, the distance between relay F and its transformer is only one-half a block-len th, while the distance between the relay an the train is a full block-length; whereas the relay in Fig. 1 ma be equally distant from its transformer an the train in another block. Consequentl whether one or two frequencies are used the arrangement of Fig. 2 possessesadvanta es, if alterhating-current of not very hi h requency is employed. If, however, hig frequency is employed for the signal-circuits, the arrange ment of Fig. 1 is as positive as that of Fig. so that the arrangement of Fig. 2 then ossesses no advantages, unless it is desire to do away with more than one frequency, In Fig. 2., for the sake of sim licity, both the er-cireuit and the signa -circuits for the hndvtrack'areiomitted; The circuits for precisely like those of thefirst trafik.

In Fig. 3 the connections for four parallel tracks are shown, the signal circuits bein omitted entirely, since t e arrangement 0 either Fig. 1 or 2 might be employed. In this figure the tracks A and A have their sectional rails connected precisely as 'm'Figs, 1 and 2, and tracks A and A havethlair se'etional rails similarly connected, but in addition to this, the remaining sections of track ,Aare connected in series with the remaining sections of track A, so as to form still an other continuous conductor. Thus, th four parallel tracks, seven'eighths of the rails are usefull employed as return for the power current; he reason that the remaining sections of tracks Al-and A are not connected to form still another: conductor is that, if

' this connection were made and trains were in i might interiors with the proper operation of the circuit." Biit it is always '-possible',by

means of my invention, to connect the sec- .ti'onal rails without intcrference'so as to form a number of continuous conductorsonly one less than the number of tracks. 1-

I donot desire, to limit myself to the particular connectionsand arrangement of parts shown, but aim in the appended claims to cover all modifications which are within the '25 scape of my invention.

.do .not in this fapplication make any claim to thecoinbinatron ofsources of ourrent of. different character connected across the rails, a continuous rail circuit between the'sources, and relays connected across the rails between-the sources, for such acdrnbination is comprised in the subject matterof my prior application, Serial ,No. 329,347,;

- having one rail sectionedto form signalfiled Au 6 1906. a a What claim as new and desire to secure by Letters Pa'tent of the United Stat-es, is,- 1. In'an electric railway em loying trackrails as return conductor for t e power-current, a'plurality of parallel tracks ea'ch'hav- 40 mg onerail conductively continuous for all currents and the other sectioned to form si'g-' nal blocks, and connections conductive for all currents between rail sections-of difie'rent tracks arranged to form with said sections a.

continuous conductor for power-current in dependent of the continuous rails.

2. In an electric railway employing the track-rails as return condu ctor' for the powercurrent, a plurality'of parallel tracks each .50 having one rail conductively' continuous for all currents and the othcrsectioncd to form signaleblocks, and connections conductive for all currents between both ends of alternate rail-sections of one track and the adja- 56 cent ends of adjacent sections of another track, said connections forming with said rail-sections a continuous jconductor for poilver-current indtpenden t-of the-continuous re: s. t 3. in an electric railway employing the track-ref l: as .relurii conductor for the powercurrent, a plurality of parallel tracks each having one rail'Suei-iuned to form signala s j 929,591 3 blocks, connections betweemboth ends of alternate rail sections on one rack to the adjacent ends of adjacent "sections of another track, sources of current connected to the rails of .the several blocks, the sources connected to ad'acent blocks of the same track, thesectional rails of which are electrically connected, differing in character, and signs controlling relays connected to the rails, the relays cqnnected to said electrically-connected a scent, locks being responsive onlyto'c reritsr' the character supplied to those blocks;

' 4. In an eljetric railway employing the track-rails as relurn conductor for the powerc\1rrent,:a=plur'ality of parallel tracks each having one rai sectioned to form signal blocks, connections between both ends of aigtemate 'rail sections 0i one track to the adjacent ends of adjacent sections of another track, sources of alternating current connected to the rails of the several blocks, the sources connectedto adjacent blocks of the 'sa e track; the sectional rails of which are lectrically connected, bein of different 1'1'e quenc "and signal-centre g relays connecte to the rails, the relays connected to said 'elclctricallyconnected ad'acent blocks being responsive to currents 0 only one frequenriyli 5. an. electr c railway employing the track-rails as return conductor for the powercurrent, a plurality of parallel tracks each blocks, connections between both ends of a1 ternatesrail sections of one track tothe adjaccnt ends of adjacent sections of another 100.

track, sources of current connected to the rails of the several blocks, these blocks, the sectional rails of which are connected to 3 other blocks, having their sources connected all currents between rail sections of dii 'erent 11 6 tracks arranged to form with said sections a number of independeht continuous conductors fin-the power-current one less than the number of tracks.

7 In witness whereof, Ihave hcreunto'set my hand this 20th day of September,-1906.'

LAURENCE A..1-IAWKINS..

Withcsses;

Ban-nuns B. HULL, HELEN Qnronn. 

